Pain Flashcards

1
Q

A-beta fibers

A

non-noxious mechanical stimulus

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2
Q

A-delta fibers

A

noxious mechanical stimulus

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3
Q

C fiber

A

noxious heat and chemical stimuli

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4
Q

Are pain signals mainly contralateral or ipsilateral?

A

contralateral

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5
Q

arrange the following from least to most myelinated:
- A-delta fibers
- C fiber
- A-beta fibers

A

C fiber < A-delta < A-beta

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6
Q

nociception

A

neural encoding of pain

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7
Q

pain

A

unpleasant sensory and EMOTIONAL experience associated with actual/potential damage

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8
Q

analgesic

A

block pain sensation ONLY

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9
Q

local anesthetic

A

block nerve conduction and ALL sensation

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10
Q

general anesthetic

A

cause unconsciousness (not always analgesia)

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11
Q

hyperalgesia

A

enhanced response to painful stimulus

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12
Q

allodynia

A

generation of painful response to an innocuous stimulus

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13
Q

Which fiber is associated with first pain and second pain?

A

first pain = A-d fibers
second pain = C fibers

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14
Q

What is acute pain treated with?

A

local anesthetics

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15
Q

what is chronic/persistent pain caused?

A

release of bradykinin, histamine acid metabolites, and prostaglandins (inflammatory factors)

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16
Q

What is chronic pain treated with?

A

non-steroidal anti-inflammatory drugs
(i.e. NSAIDs like aspirin or ibuprofen)

17
Q

what is deep pain treated with?

A

major analgesics (opioids) such as morphine

18
Q

What is neuropathic pain defined as?

A

“pain induced by injury to/disease of the somatosensory system”

(i.e. resulting from nerve injury or infections of the nervous system)

19
Q

examples of neuropathic pain

A
  • phantom limb pain
  • trigeminal neuralgia
  • shingles
  • diabetic neuropathy
  • fibromyalgia
20
Q

key point to remember about neuropathic pain?

A

outlasts healing of original injury

21
Q

clinical features of neuropathic pain

A
  • allodynia
  • hyperalgesia
  • causalgia
  • shooting pains
22
Q

List the endogenous opioids

A
  • met- and leu-enkephalin
  • beta-endorphins
  • dynorphins
  • endomorphins
23
Q

what is the opioid receptor mechanism of action on neurons?

A
  • Gi/o
  • 1) inhibit adnenylyl cyclase –> lower cAMP
  • 2) increased K+ conductance (hyperpolarization)
  • 3) suppression of N-type Ca2+ channel current
  • 4) decreased NT release
24
Q

describe the descending path of pain signal modulation (i.e. what is the source of endogenous opioids? where do inhibitory signals go?)

A
  • PAG = source of endogenous opioids
  • send inhibitory signals toward RVM and spinal dorsal horn
25
Q

What are the opioid sites of action?

A
  1. PNS –> reduce neurogenic inflammation
  2. cingulate cortex –> alter suffering (psychological response to pain)
  3. terminals of afferent A-d and C fibers in dorsal horn of SC –> reduce NT release
  4. N-type Ca2+ channels –> reduce release of acidic AA and co-transmitter Substance P in substantia gelatinosa
26
Q

What are the pain fibers?

A
  • A-d
  • C
27
Q

how do opioids modulate/disable descending pain? (hint: inhibition)

A

opioids inhibit GABA interneurons from inhibiting endogenous pain inhibitory mechanisms

28
Q

What do differences in the properties of different opioids result from?

A

differences in:
- pharmacokinetics
- affinity for different opioid receptor subtypes

29
Q

What are the opioid receptor sites?

A

MOR, DOR, KOR

30
Q

List the major effects of opioids.

A
  1. analgesia
  2. sedation and mental clouding
  3. euphoria and tranquility
  4. antitussive
  5. depression of respiratory center (prebotzinger complex)
  6. nausea, vomiting
31
Q

which opioid receptors are involved in analgesia?

A

MOR and KOR

32
Q

Which opioid receptors are involved in euophoria?

A

MOR and DOR

33
Q

which opioids’ side effects can be used to control diarrhea?

A
  • diphenoxylate
  • loperamide
34
Q

which opioid’s side effects can be used to suppress cough?

A

dextromethorphan